The ATP Tour is the modern top-level men's professional tennis circuit.
It was introduced in 1990 and it's administered by the Association of Tennis Professionals (ATP).
[2] This is the class of tournaments in which the winner earns 500 ATP ranking points.
This is the class of tournaments in which the winner earns 250 ATP ranking points.
Prize money has increased throughout the Open Era, in some cases greatly in a short time span.